Symonds has made a strong impression with Kent, most notably when he smashed the fastest century in Twenty20 cricket with a 43-ball 112 against Middlesex earlier this month.
Kent director of cricket Simon Willis said his departure had been agreed by the County and Cricket Australia (CA).
"That is that. We won't see him again this season," Willis said.
Australia want Symonds fully fit for the International Cricket Council (ICC) Champions Trophy, which will be held in England in September.
Their decision comes as a huge blow to Kent, who are riding high in the County championship, a title they have not won since 1978.
The County will now try to bring forward the arrival of his fellow Australian all-rounder Michael Bevan, who had been due to arrive in time for Symonds departure for Champions Trophy duty on August 15.
"Michael Bevan is not currently playing cricket so it will be a matter of trying to sort out with him how soon he can come," Willis added.
"He will have personal commitments but we obviously want him here sooner rather than later."